【正文】
D3 加共享鎖失敗 53假設關系 RU,F,U= {A1,A2, A3}, F = {A1A3 →A2,A1A2 →A3}, 則關系 R 的各候選關鍵字中必定含有屬性()。 SP P 需要生成一個獨立的關系模式, 其聯(lián)系類型為(54)給定關系模式 SP P(供應商號,項目號,零件號,數(shù)量) 查詢至少供應了 3 個項目(包含 3 項) 的供應商, 輸出其供應商號和供應零件數(shù)量的總和, 并按供應商號降序排列。A.*:*:* :*:* :1:* :1:1 P COUNT(項目號)2 COUNT(項目號)2 COUNT(DISTINCT(項目號))2 COUNT(DISTINCT(項目號))3 57以下關于字符串的敘述中, 正確的是()B. 字符串不是線性數(shù)據(jù)結構C. 字符串的長度是指串中所含字符的個數(shù)D. 字符串的長度是指串中所含非空格字符的個數(shù) 58已知棧 S 初始為空, 用 I 表示入棧、 O 表示出棧, 若入棧序列為 a1a2a3a4a5, 則通過棧 S 得到出棧序列 a2a4a5a3a1的合法操作序列() 59某二叉樹的先序遍歷序列為 ABCDEF ,中序遍歷序列為BADCFE ,則該二叉樹的高度(即層數(shù))為() 60對于 n 個元素的關鍵宇序列{k1,k2, ...kn}, 當且僅當滿足關系 ki≤k2i且 ki≤k2i+1{i=...[n/2]} 時稱其為小根堆(小頂堆)。,25,40,55,30,50,45 ,40,25,50,45,30,55,25,39.,41,45,43,50 ,40,25,53,39,55,45 61在 12 個互異元素構成的有序數(shù)組 a[1..12] 中進行二分查找(即折半查找, 向下取 整), 若待查找的元素正好等于 a[9][, 則在此過程中, 依次與數(shù)組中的()比較后, 查找成功結束。汽車底盤開始到進入兩條裝配線的時間(e1,e2)以及裝配后到結束的時間(X1X2)也可能不相同。現(xiàn)在要以最快的時間完成一輛汽車的裝配,求最優(yōu)的裝配路線。以L1為例,除了第一個工位之外,經(jīng)過第j個工位的最短時間包含了經(jīng)過L1的第j1個工位的最短時間或者經(jīng)過L2的第j1個工位的最短時間,如式(1)。由于在求解經(jīng)過 L1 和 L2 的第 j 個工位的最短時間均包含了經(jīng)過L1 的第 j1 個工位的最短時間或者經(jīng)過 L2 的第 j1 個工位的最短時間, 該問題具有重復子問題的性質, 故采用迭代方法求解。 DNS 緩存 hosts 文件 DNS 服務器 67下面關于 Linux 目錄的描述中, 正確的是() 只有一個根目錄, 用 /root 表示B. Linux 中有多個根目錄, 用/加相應目錄名稱表示C. Linux 中只有一個根目錄, 用/表示D. Linux 中有多個根目錄, 用相應目錄名稱表示 68以下關于 TCP/IP 協(xié)議棧中協(xié)議和層次的對應關系正確的是() 69在異步通信中, 每個字符包含 1 位起始位、 7 位數(shù)據(jù)位和 2 位終止位, 若每秒鐘傳送 500 個字符, 則有效數(shù)據(jù)速率為() 70以下路由策略中, 依據(jù)網(wǎng)絡信息經(jīng)常更新路由的是() 試題 7175The beauty of software is in its function, in its internal structure, and in the way in which it is created by a team. To a user, a program with just the right features presented through an intuitive and(71)interface is a software designer, an internal structure that is partitioned in a simple and intuitive manner, and that minimizes internal coupling is developers and managers , a motivated team of developers making significant progress every week, and producing defectfree code, is is beauty on all these levels. our world needs softwarelots of software. Fifty years ago software was something that ran in a few big and expensive machines. Thirty years ago it was something that ran in most panies and industrial settings. Now there is software running in our cell phones, watches, appliances, automobiles,toys, and tools. And need for new and better software never(72).Asour civilization grows and expands, as developing nations build their infrastructures, as developed nations strive to achieve ever greater efficiencies, the need for more and more Software(73)to increase. It would be a great shame if, in all that software, there was no beauty.We know that software can be ugly. We know that it can be hard to use, unreliable , and carelessly structured. We know that there are software systems whose tangled and careless internal structures make them expensive and difficult to change. We know that there are software systems that present their features